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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Uncovering the driving forces of carbon dioxide emissions in Chinese manufacturing industry: An intersectoral analysis

As the pillar of national economy, manufacturing industry is the largest primary energy consumer and emitter of carbon dioxide (CO2) in China. Therefore, capturing the determinants of CO2 emissions in manufacturing industry is extremely important for national efforts to mitigate carbon emissions. This paper explores the major driving forces behind CO2 emission changes in China's manufacturing industry during 2000-2015 from perspectives of the whole sector and 28 subsectors, by applying the temporal logarithmic mean Divisia index (LMDI) method. Moreover, an intersectoral LMDI model is built to uncover the intersectoral discrepancies of CO2 emissions among 28 subsectors. The temporal analysis indicates that industrial activity and energy intensity are crucial factors respectively contributing to the increase and mitigation of CO2 emissions. The intersectoral analysis reveals that energy intensity is the dominant factor responsible for the intersectoral discrepancies of CO2 emissions among 28 subsectors. The great mitigation towards CO2 emissions can be achieved if energy efficiency is largely improved in carbon-intensive subsectors. Priority should be given by governments to the industrial technology advancement, such as subsidies for energy-saving technological transformation and promotion of international advanced techniques and equipment, which can greatly improve production efficiency and mitigate emissions in manufacturing industry.

China↗
DOE OSTI2019

Kinetics and Mechanisms of Dolime Dissolution in Steelmaking Slag

The kinetics of dolime dissolution containing 20 and 50 pct of magnesium oxide in steelmaking slags has been studied in a high-temperature experiment. The dissolution tests were carried out under static conditions at temperatures of between 1573 K and 1873 K (1300 °C to 1600 °C). Cylindrical samples of dolime were introduced into pre-melted slag at predetermined time intervals. The changes in mass and geometrical parameters of the samples, as well as CaO and MgO concentrations in the melt, were determined to calculate mass transfer and diffusion coefficients. The results revealed that the rate-limiting step in the process of dolime dissolution is diffusion. The increase in MgO content in the initial sample caused a drop in dolime dissolution rate and diffusion coefficients. The prediction of MgO solubility in steel slag, as well as the effect of slag basicity, was carried out using the thermodynamic software FactSage 7.1. In addition, the activation energy of diffusion has been calculated using the dependence of the logarithm of diffusion coefficients on the inverse temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Insight into the Relationship Between Viscosity and Structure of CaO-SiO{sub 2}-MgO-Al{sub 2}O{sub 3} Molten Slags

This article elucidates the quantitative relationship between viscosity and structure in a basic slag system of CaO-SiO{sub 2}-MgO-Al{sub 2}O{sub 3} and focuses on the role of Al{sub 2}O{sub 3}. Slag viscosity was measured by the rotating cylinder method, and structural information was obtained using Fourier transformation infrared, Raman and magic angular spinning nuclear magnetic resonance (MAS-NMR) techniques. The results show that, as the Al{sub 2}O{sub 3} content increased, slag viscosity increased initially and decreased afterwards, directly indicating that Al{sub 2}O{sub 3} had an amphoteric effect on slag viscosity. The Raman spectra verified that with increasing Al{sub 2}O{sub 3} content, the concentrations of Q{sup 0}(Si) and Q{sup 2}(Si) decreased first and then increased, while that of Q{sup 1}(Si) kept increasing and that of Q{sup 3}(Si) increased first and then decreased. The {sup 27}Al MAS-NMR spectra proved that the mole ratios of AlO{sub 5} and AlO{sub 6} to AlO{sub 4} kept increasing with the increase of Al{sub 2}O{sub 3} content, and, overall, Al{sub 2}O{sub 3} changed from a network former to a network modifier. The relationship between the viscosity and structure of the molten slags was further analyzed quantitatively based on the modified (NBO/T), denoted as (NBO/T)′, and we found a fine linear correlation between the logarithm of viscosity and (NBO/T)′. Moreover, the variations of thermodynamic properties of this system also indirectly supported the present experimental results.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Effect of Plate Hardening Behavior on the Deformation of Stainless Steel Metal Bellows

Tensile tests of original plate samples from three types of stainless steel metal bellows were performed at room temperature. The constitutive equations for the three hardening curves were obtained and fitted. The analysis results of the microstructure and fracture morphology of the tensile specimens show that the grain size of the plate with a high logarithmic–exponential hardening rate is uneven and the dimple of the shear fracture is elongated into an ellipse. By contrast, the grain size of the plate with a relatively low linear hardening rate is even and the dimple of the fracture is uniformly equiaxial. Finite element simulations of the hydraulic bulging and repeated limit bending deformation of the metal bellows of the three types of materials were also conducted. The repeated limit bending deformation process was tested experimentally. Although the effect of the hardening exponent on the residual stress of the metal bellows after hydraulic bulging is minimal, this exponent considerably influences the repeated limit bending deformation of the metal bellows after subsequent use. The trough hardening phenomenon is serious in the repeated limit bending process. Moreover, when the hardening exponent of the original plate is high, the resistance to bending fracture at the trough area is poor.

36 MATERIALS SCIENCE↗
DOE OSTI2018

High-Temperature Low-Cycle Fatigue Behavior of HS80H Ferritic–Martensitic Steel Under Dynamic Strain Aging

In this work, low-cycle fatigue tests were performed on HS80H ferritic–martensitic steel with the strain amplitudes ranging from 0.5 to 2.0% at room temperature and 350 °C. The cyclic stress response at 350 °C was found to be different from that at room temperature due to the effect of dynamic strain aging and showed a significant secondary hardening when the strain values were 0.5 and 0.7%. Furthermore, the dynamic strain aging effect also resulted in an abnormal increase in fatigue life when the strain was 0.7%, which was due to the change in elastic strain. Additionally, the elastic strain and fatigue life were bilinear relations in the double logarithmic coordinates. Finally, the transmission electron microscope observations showed that the dynamic strain aging led to the change in substructure, while the grain was refined.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Evolution of Crystallographic Structure of M{sub 23}C{sub 6} Carbide Under Thermal Aging of P91 Steel

The structural changes of P91 steel after different heat treatment and M{sub 23}C{sub 6} lattice expansion are well described by JMA kinetics law; however, the role of molybdenum on the M{sub 23}C{sub 6} lattice expansion is not clearly revealed. The aim of the present work is to investigate the solubility of molybdenum in M{sub 23}C{sub 6} lattice when iron or chromium atoms are replaced by molybdenum and to examine the effect of crystallographic structure changes on the mechanical properties of thermal aged P91 steel. Rietveld analysis of electrochemically extracted residues from the as-received and thermally aged at 600, 650 and 700 °C steel revealed that it is possible to measure and evaluate quantitatively the fraction of 8c crystallographic site occupation by molybdenum atoms of the M{sub 23}C{sub 6} lattice. It was shown that the value of the site occupation factor plotted in natural logarithmic scale increases linearly and obeys Johnson–Mehl–Avrami kinetic law, giving Avrami exponent n{sub avg} = 0.3356 and activation energy E = 272 kJ/mol. Hardness measurements of the aged samples indicate that the deterioration of properties is closely coherent to the growth of crystallite size.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Measurement of advective soil gas flux: Results of field and laboratory experiments with CO2

We modified our multi-channel, steady-state flow-through (SSFT), soil-CO2 flux monitoring system to include an array of inexpensive pyroelectric non-dispersive infrared detectors for full-range (0-100%) coverage of CO2 concentrations without dilution, and a larger-diameter vent tube. We then conducted field testing of this system from late July through mid-September 2010 at the Zero Emissions Research and Technology (ZERT) project site located in Bozeman, MT, and subsequently, laboratory testing at the Pacific Northwest National Laboratory (PNNL) in Richland, WA using a flux bucket filled with dry sand. In the field, an array of twenty-five SSFT and three non-steady-state (NSS) flux chambers was installed in a 10x4 m area, the long boundary of which was directly above a shallow (2-m depth) horizontal injection well located 0.5 m below the water table. Two additional chambers (one SSFT and one NSS) were installed 10 m from the well for background measurements. Volumetric soil moisture sensors were installed at each SSFT chamber to measure mean levels in the top 0.15 m of soil. A total flux of 52 kg CO2 d-1 was injected into the well for 27 d and the efflux from the soil was monitored by the chambers before, during, and for 27 d after the injection. Overall, the results were consistent with those from previous years, showing a radial efflux pattern centered on a known “hot spot”, rapid responses to changes in injection rate and wind power, evidence for movement of the CO2 plume during the injection, and nominal flux levels from the SSFT chambers that were up to 6-fold higher than those measured by adjacent NSS chambers. Soil moisture levels varied during the experiment from moderate to near saturation with the highest levels occurring consistently at the hot spot. The effects of wind on measured flux were complex and decreased as soil moisture content increased. In the laboratory, flux bucket testing with the SSFT chamber showed large measured-flux enhancement due to the Venturi effect on the chamber vent, but an overall decrease in measured flux when wind also reached the sand surface. Flux-bucket tests at a high flux (comparable to that at the hot spot) also showed that the measured flux levels increase linearly with the chamber-flushing rate until the actual level is reached. At the SSFT chamber-flushing rate used in the field experiment the measured flux in the laboratory was only about a third of the actual flux. The ratio of measured to actual flux increased logarithmically as flux decreased, and reached parity at low levels typical of diffusive flux systems. Taken together, our results suggest that values for advective CO2 flux measured by SSFT and NSS chamber systems are likely to be significantly lower than the actual values due to back pressure developed in the chamber that diverts flux from entering the chamber. Chamber designs that counteract the back pressure and also avoid large Venturi effects associated with vent tubes, such as the SSFT with a narrow vent tube operated at a high chamber-flushing rate, are likely to yield flux measurements closer to the true values.

carbon dioxide↗
DOE OSTI2020

Cavity Swelling in Irradiated Materials

Cavity swelling, due to three-dimensional clustering of vacancies, is an undesirable isotropic volume expansion of materials under irradiation. This phenomenon occurs above stage-III recovery temperature where vacancies are mobile, between ~0.3–0.6 Tm where Tm is the absolute melting temperature. The primary mechanism for cavity swelling is “dislocation bias”, i.e., preferential absorption of interstitials by network dislocations, causing a vacancy supersaturation. Cavity swelling is highly temperature dependent and typically follows a bell-shaped curve with peak swelling occurring at an intermediate temperature. With increasing temperature, cavity size increases, and number density decreases logarithmically. With increasing dose, cavity swelling increases, but follows a hockey-stick type pattern, characterized by a low-swelling transient incubation period and then a steady-state regime. The incubation period, dominant in cavity nucleation, is dependent upon material’s chemistry and irradiation conditions such as dose rate/temperature. Cavity swelling increases linearly with dose in the steady-state regime, that is independent of chemistry and dose rate. This regime is dominated by cavity growth. Transmutation gases like He enhance cavity nucleation such that an early onset of cavity formation occurs. However, swelling magnitudes can be either increased or suppressed when He is present. Results in austenitic steels and Cu indicate that cavity swelling peaks at intermediate He/dpa ratios of ~10 appm He/dpa. The most effective method to mitigate cavity swelling is by increasing the fixed point-defect sink density, by promoting precipitation or dispersion strengthening.

Bhattacharya, Arunodaya↗
DOE OSTI2011

Recovery of phosphonate surface contaminants from glass using a simple vacuum extractor with a solid-phase microextraction fiber

Recovery of chemical contaminants from fixed surfaces for analysis can be challenging particularly if it is not possible to acquire a solid sample. A simple device is described that collects semivolatile organic compounds from fixed surfaces by creating an enclosed volume over the surface, then generating a modest vacuum. A solid-phase microextraction fiber is then inserted into the evacuated volume where it functions to sorb volatilized organic contaminants. The device is based on a syringe modified with a seal that is used to create the vacuum, with a perforable plunger through which the SPME fiber is inserted. The vacuum speeds partitioning of the semivolatile compounds into the gas phase, and reduces the boundary layer around the SPME fiber, which enables a fraction of the volatilized organics to partition into the SPME fiber. After sample collection the SPME fiber is analyzed using conventional gas chromatography/mass spectrometry. The methodology has been used to collect organophosphorus compounds from glass surfaces, to provide a simple test for the functionality of the devices. Thirty minute sampling times (deltaTvac) resulted in fractional recovery efficiencies ranged from 10(-3) to > 10(-1), and in absolute terms collection of low nanograms was demonstrated. Fractional recovery values were correlated to the vapor pressure of the compounds being sampled. Fractional recovery increased with increasing deltaTvac, and displayed a roughly logarithmic profile indicating that an operational equilibrium is being approached. Fractional recovery decreased with increasing time between exposure and sampling, however recordable quantities of the phosphonates could be collected three weeks after exposure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Ten-year variability in ecosystem water use efficiency in an oak-dominated temperate forest under a warming climate

The impacts of extreme weather events on water-carbon (C) coupling and ecosystem-scale water use efficiency (WUE) over a long term are poorly understood. We analyzed the changes in ecosystem water use efficiency (WUE) from 10 years of eddy-covariance measurements (2004-2013) over an oak-dominated temperate forest in Ohio, USA. The aim was to investigate the long-term response of ecosystem WUE to measured changes in site-biophysical conditions and ecosystem attributes. The oak forest produced new plant biomass of 2.5 +/- 0.2 gC kg(-1) of water loss annually. Monthly evapotranspiration (ET) and gross ecosystem production (GEP) were tightly coupled over the 10-year study period (R-2=0.94). Daily WUE had a linear relationship with air temperature (T-a) in low-temperature months and a unimodal relationship with T-a in high-temperature months during the growing season. On average, daily WUE ceased to increase when T-a exceeded 22 degrees C in warm months for both wet and dry years. Monthly WUE had a strong positive linear relationship with leaf area index (LAI), net radiation (R-n), and T-a and weak logarithmic relationship with water vapor pressure deficit (VPD) and precipitation (P) on a growing-season basis. When exploring the regulatory mechanisms on WUE within each season, spring LAI and P, summer R-n and T-a, and autumnal VPD and R-n were found to be the main explanatory variables for seasonal variation in WUE. The model developed in this study was able to capture 78% of growing-season variation in WUE on a monthly basis. The negative correlation between WUE and A in spring was mainly due to the high precipitation amounts in spring, decreasing GEP and WUE when LAI was still small, adding ET being observed to increase with high levels of evaporation as a result of high SWC in spring. Summer WUE had a significant decreasing trend across the 10 years mainly due to the combined effect of seasonal drought and increasing potential and available energy increasing ET, but decreasing GEP in summer. We concluded that seasonal dynamics of the interchange between precipitation and drought status of the system was an important variable in controlling seasonal WUE in wet years. In contrast, despite the negative impacts of unfavorable warming, available groundwater and an early start of the growing season were important contributing variables in high seasonal GEP, and thus, high seasonal WUE in dry years. (C) 2015 Elsevier B.V. All rights reserved.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Sequential Monte Carlo sampling in hidden Markov models of nonlinear dynamical systems

We investigate the issue of which state functionals can have their uncertainty estimated efficiently in dynamical systems with uncertainty. Because of the high dimensionality and complexity of the problem, sequential Monte Carlo (SMC) methods are used. We investigate SMC methods where the proposal distribution is computed by maximum likelihood or by a linearization approach. We prove that the variance of the SMC method is bounded linearly in the number of time steps when the proposal distribution is truncated normal distribution. We also show that for a moderate large number of steps the error produced by approximation of dynamical systems linearly accumulates on the condition that the logarithm of the density function of noise is Lipschitz continuous. This finding is significant because the uncertainty in many dynamical systems, in particular, in chemical engineering systems, can be assumed to have this nature. We demonstrate our findings for a simple test case from chemical engineering. The theoretical findings provide a foundation for the parallel software SISTOS.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Mass transport analysis for tritium removal in FHRs

Tritium control and mitigation is one of the most significant issues in Fluoride Salt-cooled Hightemperature Reactors (FHRs). To address this issue, a cross-flow tritium removal facility has been proposed to remove molecular tritium, T 2 , from the primary coolant. To model the performance of the design, a method is developed based on the logarithmic mean difference of the square root of the tritium partial pressures on the upstream side and the purging gas side. A computer code has been developed based on this global analysis method to study the effectiveness of tritium removal in such a cross-flow tritium removal facility. The code is benchmarked against experimental data from a hydrogen separation experiment in the literature and compared with the results from a code based on traditional finite volume method. Evaluation of the cross-flow tritium removal facility designed for FHR systems has also been performed. The results show how the key factors, i.e., the fluid flow rates and tritium inlet concentration affect the performance of the facility.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Singular value decomposition of adjoint flux distributions for Monte Carlo variance reduction

Monte Carlo (MC) shielding calculations often use weight windows (WWs) and biased sources formed from a deterministic estimate of the adjoint flux to improve the convergence rate of tallies. This requires a significant amount of computer memory, which can limit the memory available for high-resolution tally output. A new method is proposed for reducing these memory requirements by using singular value decomposition (SVD) in linear or logarithmic space to approximate the adjoint flux. This method’s performance is evaluated using the Shift and Denovo codes for streaming and diffusion base case problems, followed by problems using the Westinghouse AP1000 and the Joint European Torus. The log SVD reduced WW memory requirements by an order of magnitude in all cases without a significant performance penalty. Additionally, the linear SVD reduced biased source memory requirements by an order of magnitude, but further investigation is needed to account for observed limitations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Lamb shift in muonic hydrogen-I. Verification and update of theoretical predictions

Research Highlights: > The QED theory of muonic hydrogen energy levels is verified and updated. > Previously obtained results of Pachucki and Borie are confirmed. > The influence of the vacuum polarization potential onto the Bethe logarithm is calculated nonperturbatively. > A model-independent estimate of the Zemach moment correction is given. > Parametrically, the observed discrepancy of theory and experiment is shown to be substantial and large. - Abstract: In view of the recently observed discrepancy of theory and experiment for muonic hydrogen [R. Pohl et al., Nature 466 (2010) 213], we reexamine the theory on which the quantum electrodynamic (QED) predictions are based. In particular, we update the theory of the 2P-2S Lamb shift, by calculating the self-energy of the bound muon in the full Coulomb + vacuum polarization (Uehling) potential. We also investigate the relativistic two-body corrections to the vacuum polarization shift, and we analyze the influence of the shape of the nuclear charge distribution on the proton radius determination. The uncertainty associated with the third Zemach moment <r{sup 3}>{sub 2} in the determination of the proton radius from the measurement is estimated. An updated theoretical prediction for the 2S-2P transition is given.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

The abelian confinement mechanism revisited: New aspects of the Georgi–Glashow model

The confinement problem remains one of the most difficult problems in theoretical physics. An important step toward the solution of this problem is Polyakov’s work on abelian confinement. The Georgi–Glashow model is a natural testing ground for this mechanism which has been surprising us by its richness and wide applicability. In this work, we shed light on two new aspects of this model in 2+1 D. First, we develop a many-body description of the effective degrees of freedom. Namely, we consider a non-relativistic gas of W-bosons in the background of monopole–instanton plasma. Many-body treatment is a standard toolkit in condensed matter physics. However, we add a new twist by supplying the monopole–instantons as external background field. Using this construction along with a mean-field approximation, we calculate the form of the potential between two electric probes as a function of their separation. This potential is expressed in terms of the Meijer-G function which interpolates between logarithmic and linear behavior at small and large distances, respectively. Second, we develop a systematic approach to integrate out the effect of the W-bosons at finite temperature in the range 0≤T<M{sub W}, where M{sub W} is the W-boson mass, starting from the full relativistic partition function of the Georgi–Glashow model. Using a heat kernel expansion that takes into account the non-trivial thermal holonomy, we show that the partition function describes a three-dimensional two-component Coulomb gas. We repeat our analysis using the many-body description which yields the same result and provides a check on our formalism. At temperatures close to the deconfinement temperature, the gas becomes essentially two-dimensional recovering the partition function of the dual sine-Gordon model that was considered in a previous work. -- Highlights: • We consider the problem of abelian confinement in the Georgi–Glashow model from a new perspective. • We develop a many-body description of the degrees of freedom of this model in the background of monopole–instanton plasma. • We use the many-body formalism to find an analytic expression of the potential between two probes at zero temperature. • We also use a systematic approach to integrate out the W-bosons starting from the full relativistic partition function. • This results in a three-dimensional two-component Coulomb gas with long range and Aharonov–Bohm phase interaction.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Enhancing non-local correlations in the bipartite partitions of two qubit-system with non-mutual interaction

Several quantum-mechanical correlations, notably, quantum entanglement, measurement-induced nonlocality and Bell nonlocality are studied for a two qubit-system having no mutual interaction. Analytical expressions for the measures of these quantum-mechanical correlations of different bipartite partitions of the system are obtained, for initially two entangled qubits and the two photons are in their vacuum states. It is found that the qubits-fields interaction leads to the loss and gain of the initial quantum correlations. The lost initial quantum correlations transfer from the qubits to the cavity fields. It is found that the maximal violation of Bell’s inequality is occurring when the quantum correlations of both the logarithmic negativity and measurement-induced nonlocality reach particular values. The maximal violation of Bell’s inequality occurs only for certain bipartite partitions of the system. The frequency detuning leads to quick oscillations of the quantum correlations and inhibits their transfer from the qubits to the cavity modes. It is also found that the dynamical behavior of the quantum correlation clearly depends on the qubit distribution angle.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗